River corridor plants revisited: What drives their unique distribution patterns?

The phenomenon whereby some plant species display a river corridor distribution pattern has long been recognized but is still poorly understood. The goals of this study were to supplement the list of river corridor plants for Central Europe, analyse their habitats and compare their ecological features with those of their widely distributed counterparts. The ATPOL (Atlas of Poland) database was used to compile a list of river corridor plants of Poland and calculate their river corridor-specificity indices (RCSIs). The Ellenberg indicator values, dispersal modes and life forms of river corridor and widely distributed species were compared using generalized linear mixed models (GLMMs). Eighty-five species were classified as river corridor species. The most numerous habitat groups were meadow species (19%), wet-habitat therophytes (15%), riverside tall herbs (13%) and species of dry, sandy soils (12%). These species had mostly requirements for a higher temperature and alkalinity than widespread species. Among river corridor plants, there were a few eurytopic species. Corridor species had usually only one life form and less dispersal modes than widespread species. Hence, specific demands of corridor plants and lower phenotypic plasticity may explain their restricted geographical distribution. The definition of the river corridor plant species needs modification.部分植物物种呈现河流廊道分布格局的现象，早已为学界所认知，但至今仍未得到充分阐释。本研究旨在补充中欧河流廊道植物名录，剖析其生境特征，并将其生态特性与广布同类物种进行对比。本研究采用ATPOL（Atlas of Poland，波兰植物志）数据库，编制波兰境内河流廊道植物名录，并计算其河流廊道特异性指数（RCSIs）。研究采用广义线性混合模型（generalized linear mixed models, GLMMs），对比河流廊道物种与广布物种的埃伦伯格指示值、传播方式及生活型。最终共有85个物种被划归为河流廊道物种。物种数量最多的生境类群依次为草甸植物（19%）、湿生一年生植物（15%）、河岸高大草本植物（13%）以及干旱沙质土壤物种（12%）。相较于广布物种，此类植物大多需要更高的温度与碱度环境。在河流廊道植物中，仅存在少量广适性物种。廊道物种通常仅具备单一生活型，且传播方式种类少于广布物种。因此，廊道物种的特异性生境需求与较低的表型可塑性，或可解释其地理分布受限的成因。当前河流廊道植物物种的定义仍需进一步修订完善。